In recent years, sheet-like displays using flexible substrates have been developed for commercialization. Sheet-like displays have been drawing attention as lightweight and flat displays. The display panel of each sheet-like display comprises a flexible insulating layer. For example, a PI film (a polyimide precursor solution film coated with a solution containing a polyimide precursor) is used for the insulating layer. In the process for manufacturing the display panel, the insulating layer is formed on a glass substrate used as a base member.
In a process for forming a plurality of display panels using a substrate, the substrate is separated from an insulating layer.
When the substrate is removed from the insulating layer, the insulating layer might be electrically charged, or a foreign substance might be electrostatically adsorbed to the insulating layer.
In a step for separating the substrate from the insulating layer, the insulating layer is removed from the substrate with laser light. To cause laser light to reach the insulating layer, the substrate is subjected to dry cleaning using a brush before laser irradiation. After the dry cleaning, the substrate chip is separated from the insulating layer.
In the step of dry cleaning using a brush and the step for removing the substrate from the insulating layer as described above, the insulating layer might be electrically charged.
If the insulating layer is electrically charged, a foreign substance might be adsorbed to the insulating layer. In addition, electrostatic discharge (ESD) failure might be caused. If ESD failure is caused, the switching elements or capacitive elements of the display panel may be destroyed.